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# # This file is part of pyasn1 software. # # Copyright (c) 2005-2020, Ilya Etingof <etingof@gmail.com> # License: https://pyasn1.readthedocs.io/en/latest/license.html # import io import os import sys import warnings from pyasn1 import debug from pyasn1 import error from pyasn1.codec.ber import eoo from pyasn1.codec.streaming import asSeekableStream from pyasn1.codec.streaming import isEndOfStream from pyasn1.codec.streaming import peekIntoStream from pyasn1.codec.streaming import readFromStream from pyasn1.compat import _MISSING from pyasn1.error import PyAsn1Error from pyasn1.type import base from pyasn1.type import char from pyasn1.type import tag from pyasn1.type import tagmap from pyasn1.type import univ from pyasn1.type import useful __all__ = ['StreamingDecoder', 'Decoder', 'decode'] LOG = debug.registerLoggee(__name__, flags=debug.DEBUG_DECODER) noValue = base.noValue SubstrateUnderrunError = error.SubstrateUnderrunError class AbstractPayloadDecoder(object): protoComponent = None def valueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): """Decode value with fixed byte length. The decoder is allowed to consume as many bytes as necessary. """ raise error.PyAsn1Error('SingleItemDecoder not implemented for %s' % (tagSet,)) # TODO: Seems more like an NotImplementedError? def indefLenValueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): """Decode value with undefined length. The decoder is allowed to consume as many bytes as necessary. """ raise error.PyAsn1Error('Indefinite length mode decoder not implemented for %s' % (tagSet,)) # TODO: Seems more like an NotImplementedError? @staticmethod def _passAsn1Object(asn1Object, options): if 'asn1Object' not in options: options['asn1Object'] = asn1Object return options class AbstractSimplePayloadDecoder(AbstractPayloadDecoder): @staticmethod def substrateCollector(asn1Object, substrate, length, options): for chunk in readFromStream(substrate, length, options): yield chunk def _createComponent(self, asn1Spec, tagSet, value, **options): if options.get('native'): return value elif asn1Spec is None: return self.protoComponent.clone(value, tagSet=tagSet) elif value is noValue: return asn1Spec else: return asn1Spec.clone(value) class RawPayloadDecoder(AbstractSimplePayloadDecoder): protoComponent = univ.Any('') def valueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if substrateFun: asn1Object = self._createComponent(asn1Spec, tagSet, '', **options) for chunk in substrateFun(asn1Object, substrate, length, options): yield chunk return for value in decodeFun(substrate, asn1Spec, tagSet, length, **options): yield value def indefLenValueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if substrateFun: asn1Object = self._createComponent(asn1Spec, tagSet, '', **options) for chunk in substrateFun(asn1Object, substrate, length, options): yield chunk return while True: for value in decodeFun( substrate, asn1Spec, tagSet, length, allowEoo=True, **options): if value is eoo.endOfOctets: return yield value rawPayloadDecoder = RawPayloadDecoder() class IntegerPayloadDecoder(AbstractSimplePayloadDecoder): protoComponent = univ.Integer(0) def valueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if tagSet[0].tagFormat != tag.tagFormatSimple: raise error.PyAsn1Error('Simple tag format expected') for chunk in readFromStream(substrate, length, options): if isinstance(chunk, SubstrateUnderrunError): yield chunk if chunk: value = int.from_bytes(bytes(chunk), 'big', signed=True) else: value = 0 yield self._createComponent(asn1Spec, tagSet, value, **options) class BooleanPayloadDecoder(IntegerPayloadDecoder): protoComponent = univ.Boolean(0) def _createComponent(self, asn1Spec, tagSet, value, **options): return IntegerPayloadDecoder._createComponent( self, asn1Spec, tagSet, value and 1 or 0, **options) class BitStringPayloadDecoder(AbstractSimplePayloadDecoder): protoComponent = univ.BitString(()) supportConstructedForm = True def valueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if substrateFun: asn1Object = self._createComponent(asn1Spec, tagSet, noValue, **options) for chunk in substrateFun(asn1Object, substrate, length, options): yield chunk return if not length: raise error.PyAsn1Error('Empty BIT STRING substrate') for chunk in isEndOfStream(substrate): if isinstance(chunk, SubstrateUnderrunError): yield chunk if chunk: raise error.PyAsn1Error('Empty BIT STRING substrate') if tagSet[0].tagFormat == tag.tagFormatSimple: # XXX what tag to check? for trailingBits in readFromStream(substrate, 1, options): if isinstance(trailingBits, SubstrateUnderrunError): yield trailingBits trailingBits = ord(trailingBits) if trailingBits > 7: raise error.PyAsn1Error( 'Trailing bits overflow %s' % trailingBits ) for chunk in readFromStream(substrate, length - 1, options): if isinstance(chunk, SubstrateUnderrunError): yield chunk value = self.protoComponent.fromOctetString( chunk, internalFormat=True, padding=trailingBits) yield self._createComponent(asn1Spec, tagSet, value, **options) return if not self.supportConstructedForm: raise error.PyAsn1Error('Constructed encoding form prohibited ' 'at %s' % self.__class__.__name__) if LOG: LOG('assembling constructed serialization') # All inner fragments are of the same type, treat them as octet string substrateFun = self.substrateCollector bitString = self.protoComponent.fromOctetString(b'', internalFormat=True) current_position = substrate.tell() while substrate.tell() - current_position < length: for component in decodeFun( substrate, self.protoComponent, substrateFun=substrateFun, **options): if isinstance(component, SubstrateUnderrunError): yield component trailingBits = component[0] if trailingBits > 7: raise error.PyAsn1Error( 'Trailing bits overflow %s' % trailingBits ) bitString = self.protoComponent.fromOctetString( component[1:], internalFormat=True, prepend=bitString, padding=trailingBits ) yield self._createComponent(asn1Spec, tagSet, bitString, **options) def indefLenValueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if substrateFun: asn1Object = self._createComponent(asn1Spec, tagSet, noValue, **options) for chunk in substrateFun(asn1Object, substrate, length, options): yield chunk return # All inner fragments are of the same type, treat them as octet string substrateFun = self.substrateCollector bitString = self.protoComponent.fromOctetString(b'', internalFormat=True) while True: # loop over fragments for component in decodeFun( substrate, self.protoComponent, substrateFun=substrateFun, allowEoo=True, **options): if component is eoo.endOfOctets: break if isinstance(component, SubstrateUnderrunError): yield component if component is eoo.endOfOctets: break trailingBits = component[0] if trailingBits > 7: raise error.PyAsn1Error( 'Trailing bits overflow %s' % trailingBits ) bitString = self.protoComponent.fromOctetString( component[1:], internalFormat=True, prepend=bitString, padding=trailingBits ) yield self._createComponent(asn1Spec, tagSet, bitString, **options) class OctetStringPayloadDecoder(AbstractSimplePayloadDecoder): protoComponent = univ.OctetString('') supportConstructedForm = True def valueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if substrateFun: asn1Object = self._createComponent(asn1Spec, tagSet, noValue, **options) for chunk in substrateFun(asn1Object, substrate, length, options): yield chunk return if tagSet[0].tagFormat == tag.tagFormatSimple: # XXX what tag to check? for chunk in readFromStream(substrate, length, options): if isinstance(chunk, SubstrateUnderrunError): yield chunk yield self._createComponent(asn1Spec, tagSet, chunk, **options) return if not self.supportConstructedForm: raise error.PyAsn1Error('Constructed encoding form prohibited at %s' % self.__class__.__name__) if LOG: LOG('assembling constructed serialization') # All inner fragments are of the same type, treat them as octet string substrateFun = self.substrateCollector header = b'' original_position = substrate.tell() # head = popSubstream(substrate, length) while substrate.tell() - original_position < length: for component in decodeFun( substrate, self.protoComponent, substrateFun=substrateFun, **options): if isinstance(component, SubstrateUnderrunError): yield component header += component yield self._createComponent(asn1Spec, tagSet, header, **options) def indefLenValueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if substrateFun and substrateFun is not self.substrateCollector: asn1Object = self._createComponent(asn1Spec, tagSet, noValue, **options) for chunk in substrateFun(asn1Object, substrate, length, options): yield chunk return # All inner fragments are of the same type, treat them as octet string substrateFun = self.substrateCollector header = b'' while True: # loop over fragments for component in decodeFun( substrate, self.protoComponent, substrateFun=substrateFun, allowEoo=True, **options): if isinstance(component, SubstrateUnderrunError): yield component if component is eoo.endOfOctets: break if component is eoo.endOfOctets: break header += component yield self._createComponent(asn1Spec, tagSet, header, **options) class NullPayloadDecoder(AbstractSimplePayloadDecoder): protoComponent = univ.Null('') def valueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if tagSet[0].tagFormat != tag.tagFormatSimple: raise error.PyAsn1Error('Simple tag format expected') for chunk in readFromStream(substrate, length, options): if isinstance(chunk, SubstrateUnderrunError): yield chunk component = self._createComponent(asn1Spec, tagSet, '', **options) if chunk: raise error.PyAsn1Error('Unexpected %d-octet substrate for Null' % length) yield component class ObjectIdentifierPayloadDecoder(AbstractSimplePayloadDecoder): protoComponent = univ.ObjectIdentifier(()) def valueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if tagSet[0].tagFormat != tag.tagFormatSimple: raise error.PyAsn1Error('Simple tag format expected') for chunk in readFromStream(substrate, length, options): if isinstance(chunk, SubstrateUnderrunError): yield chunk if not chunk: raise error.PyAsn1Error('Empty substrate') oid = () index = 0 substrateLen = len(chunk) while index < substrateLen: subId = chunk[index] index += 1 if subId < 128: oid += (subId,) elif subId > 128: # Construct subid from a number of octets nextSubId = subId subId = 0 while nextSubId >= 128: subId = (subId << 7) + (nextSubId & 0x7F) if index >= substrateLen: raise error.SubstrateUnderrunError( 'Short substrate for sub-OID past %s' % (oid,) ) nextSubId = chunk[index] index += 1 oid += ((subId << 7) + nextSubId,) elif subId == 128: # ASN.1 spec forbids leading zeros (0x80) in OID # encoding, tolerating it opens a vulnerability. See # https://www.esat.kuleuven.be/cosic/publications/article-1432.pdf # page 7 raise error.PyAsn1Error('Invalid octet 0x80 in OID encoding') # Decode two leading arcs if 0 <= oid[0] <= 39: oid = (0,) + oid elif 40 <= oid[0] <= 79: oid = (1, oid[0] - 40) + oid[1:] elif oid[0] >= 80: oid = (2, oid[0] - 80) + oid[1:] else: raise error.PyAsn1Error('Malformed first OID octet: %s' % chunk[0]) yield self._createComponent(asn1Spec, tagSet, oid, **options) class RelativeOIDPayloadDecoder(AbstractSimplePayloadDecoder): protoComponent = univ.RelativeOID(()) def valueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if tagSet[0].tagFormat != tag.tagFormatSimple: raise error.PyAsn1Error('Simple tag format expected') for chunk in readFromStream(substrate, length, options): if isinstance(chunk, SubstrateUnderrunError): yield chunk if not chunk: raise error.PyAsn1Error('Empty substrate') reloid = () index = 0 substrateLen = len(chunk) while index < substrateLen: subId = chunk[index] index += 1 if subId < 128: reloid += (subId,) elif subId > 128: # Construct subid from a number of octets nextSubId = subId subId = 0 while nextSubId >= 128: subId = (subId << 7) + (nextSubId & 0x7F) if index >= substrateLen: raise error.SubstrateUnderrunError( 'Short substrate for sub-OID past %s' % (reloid,) ) nextSubId = chunk[index] index += 1 reloid += ((subId << 7) + nextSubId,) elif subId == 128: # ASN.1 spec forbids leading zeros (0x80) in OID # encoding, tolerating it opens a vulnerability. See # https://www.esat.kuleuven.be/cosic/publications/article-1432.pdf # page 7 raise error.PyAsn1Error('Invalid octet 0x80 in RELATIVE-OID encoding') yield self._createComponent(asn1Spec, tagSet, reloid, **options) class RealPayloadDecoder(AbstractSimplePayloadDecoder): protoComponent = univ.Real() def valueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if tagSet[0].tagFormat != tag.tagFormatSimple: raise error.PyAsn1Error('Simple tag format expected') for chunk in readFromStream(substrate, length, options): if isinstance(chunk, SubstrateUnderrunError): yield chunk if not chunk: yield self._createComponent(asn1Spec, tagSet, 0.0, **options) return fo = chunk[0] chunk = chunk[1:] if fo & 0x80: # binary encoding if not chunk: raise error.PyAsn1Error("Incomplete floating-point value") if LOG: LOG('decoding binary encoded REAL') n = (fo & 0x03) + 1 if n == 4: n = chunk[0] chunk = chunk[1:] eo, chunk = chunk[:n], chunk[n:] if not eo or not chunk: raise error.PyAsn1Error('Real exponent screwed') e = eo[0] & 0x80 and -1 or 0 while eo: # exponent e <<= 8 e |= eo[0] eo = eo[1:] b = fo >> 4 & 0x03 # base bits if b > 2: raise error.PyAsn1Error('Illegal Real base') if b == 1: # encbase = 8 e *= 3 elif b == 2: # encbase = 16 e *= 4 p = 0 while chunk: # value p <<= 8 p |= chunk[0] chunk = chunk[1:] if fo & 0x40: # sign bit p = -p sf = fo >> 2 & 0x03 # scale bits p *= 2 ** sf value = (p, 2, e) elif fo & 0x40: # infinite value if LOG: LOG('decoding infinite REAL') value = fo & 0x01 and '-inf' or 'inf' elif fo & 0xc0 == 0: # character encoding if not chunk: raise error.PyAsn1Error("Incomplete floating-point value") if LOG: LOG('decoding character encoded REAL') try: if fo & 0x3 == 0x1: # NR1 value = (int(chunk), 10, 0) elif fo & 0x3 == 0x2: # NR2 value = float(chunk) elif fo & 0x3 == 0x3: # NR3 value = float(chunk) else: raise error.SubstrateUnderrunError( 'Unknown NR (tag %s)' % fo ) except ValueError: raise error.SubstrateUnderrunError( 'Bad character Real syntax' ) else: raise error.SubstrateUnderrunError( 'Unknown encoding (tag %s)' % fo ) yield self._createComponent(asn1Spec, tagSet, value, **options) class AbstractConstructedPayloadDecoder(AbstractPayloadDecoder): protoComponent = None class ConstructedPayloadDecoderBase(AbstractConstructedPayloadDecoder): protoRecordComponent = None protoSequenceComponent = None def _getComponentTagMap(self, asn1Object, idx): raise NotImplementedError def _getComponentPositionByType(self, asn1Object, tagSet, idx): raise NotImplementedError def _decodeComponentsSchemaless( self, substrate, tagSet=None, decodeFun=None, length=None, **options): asn1Object = None components = [] componentTypes = set() original_position = substrate.tell() while length == -1 or substrate.tell() < original_position + length: for component in decodeFun(substrate, **options): if isinstance(component, SubstrateUnderrunError): yield component if length == -1 and component is eoo.endOfOctets: break components.append(component) componentTypes.add(component.tagSet) # Now we have to guess is it SEQUENCE/SET or SEQUENCE OF/SET OF # The heuristics is: # * 1+ components of different types -> likely SEQUENCE/SET # * otherwise -> likely SEQUENCE OF/SET OF if len(componentTypes) > 1: protoComponent = self.protoRecordComponent else: protoComponent = self.protoSequenceComponent asn1Object = protoComponent.clone( # construct tagSet from base tag from prototype ASN.1 object # and additional tags recovered from the substrate tagSet=tag.TagSet(protoComponent.tagSet.baseTag, *tagSet.superTags) ) if LOG: LOG('guessed %r container type (pass `asn1Spec` to guide the ' 'decoder)' % asn1Object) for idx, component in enumerate(components): asn1Object.setComponentByPosition( idx, component, verifyConstraints=False, matchTags=False, matchConstraints=False ) yield asn1Object def valueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if tagSet[0].tagFormat != tag.tagFormatConstructed: raise error.PyAsn1Error('Constructed tag format expected') original_position = substrate.tell() if substrateFun: if asn1Spec is not None: asn1Object = asn1Spec.clone() elif self.protoComponent is not None: asn1Object = self.protoComponent.clone(tagSet=tagSet) else: asn1Object = self.protoRecordComponent, self.protoSequenceComponent for chunk in substrateFun(asn1Object, substrate, length, options): yield chunk return if asn1Spec is None: for asn1Object in self._decodeComponentsSchemaless( substrate, tagSet=tagSet, decodeFun=decodeFun, length=length, **options): if isinstance(asn1Object, SubstrateUnderrunError): yield asn1Object if substrate.tell() < original_position + length: if LOG: for trailing in readFromStream(substrate, context=options): if isinstance(trailing, SubstrateUnderrunError): yield trailing LOG('Unused trailing %d octets encountered: %s' % ( len(trailing), debug.hexdump(trailing))) yield asn1Object return asn1Object = asn1Spec.clone() asn1Object.clear() options = self._passAsn1Object(asn1Object, options) if asn1Spec.typeId in (univ.Sequence.typeId, univ.Set.typeId): namedTypes = asn1Spec.componentType isSetType = asn1Spec.typeId == univ.Set.typeId isDeterministic = not isSetType and not namedTypes.hasOptionalOrDefault if LOG: LOG('decoding %sdeterministic %s type %r chosen by type ID' % ( not isDeterministic and 'non-' or '', isSetType and 'SET' or '', asn1Spec)) seenIndices = set() idx = 0 while substrate.tell() - original_position < length: if not namedTypes: componentType = None elif isSetType: componentType = namedTypes.tagMapUnique else: try: if isDeterministic: componentType = namedTypes[idx].asn1Object elif namedTypes[idx].isOptional or namedTypes[idx].isDefaulted: componentType = namedTypes.getTagMapNearPosition(idx) else: componentType = namedTypes[idx].asn1Object except IndexError: raise error.PyAsn1Error( 'Excessive components decoded at %r' % (asn1Spec,) ) for component in decodeFun(substrate, componentType, **options): if isinstance(component, SubstrateUnderrunError): yield component if not isDeterministic and namedTypes: if isSetType: idx = namedTypes.getPositionByType(component.effectiveTagSet) elif namedTypes[idx].isOptional or namedTypes[idx].isDefaulted: idx = namedTypes.getPositionNearType(component.effectiveTagSet, idx) asn1Object.setComponentByPosition( idx, component, verifyConstraints=False, matchTags=False, matchConstraints=False ) seenIndices.add(idx) idx += 1 if LOG: LOG('seen component indices %s' % seenIndices) if namedTypes: if not namedTypes.requiredComponents.issubset(seenIndices): raise error.PyAsn1Error( 'ASN.1 object %s has uninitialized ' 'components' % asn1Object.__class__.__name__) if namedTypes.hasOpenTypes: openTypes = options.get('openTypes', {}) if LOG: LOG('user-specified open types map:') for k, v in openTypes.items(): LOG('%s -> %r' % (k, v)) if openTypes or options.get('decodeOpenTypes', False): for idx, namedType in enumerate(namedTypes.namedTypes): if not namedType.openType: continue if namedType.isOptional and not asn1Object.getComponentByPosition(idx).isValue: continue governingValue = asn1Object.getComponentByName( namedType.openType.name ) try: openType = openTypes[governingValue] except KeyError: if LOG: LOG('default open types map of component ' '"%s.%s" governed by component "%s.%s"' ':' % (asn1Object.__class__.__name__, namedType.name, asn1Object.__class__.__name__, namedType.openType.name)) for k, v in namedType.openType.items(): LOG('%s -> %r' % (k, v)) try: openType = namedType.openType[governingValue] except KeyError: if LOG: LOG('failed to resolve open type by governing ' 'value %r' % (governingValue,)) continue if LOG: LOG('resolved open type %r by governing ' 'value %r' % (openType, governingValue)) containerValue = asn1Object.getComponentByPosition(idx) if containerValue.typeId in ( univ.SetOf.typeId, univ.SequenceOf.typeId): for pos, containerElement in enumerate( containerValue): stream = asSeekableStream(containerValue[pos].asOctets()) for component in decodeFun(stream, asn1Spec=openType, **options): if isinstance(component, SubstrateUnderrunError): yield component containerValue[pos] = component else: stream = asSeekableStream(asn1Object.getComponentByPosition(idx).asOctets()) for component in decodeFun(stream, asn1Spec=openType, **options): if isinstance(component, SubstrateUnderrunError): yield component asn1Object.setComponentByPosition(idx, component) else: inconsistency = asn1Object.isInconsistent if inconsistency: raise error.PyAsn1Error( f"ASN.1 object {asn1Object.__class__.__name__} is inconsistent") else: componentType = asn1Spec.componentType if LOG: LOG('decoding type %r chosen by given `asn1Spec`' % componentType) idx = 0 while substrate.tell() - original_position < length: for component in decodeFun(substrate, componentType, **options): if isinstance(component, SubstrateUnderrunError): yield component asn1Object.setComponentByPosition( idx, component, verifyConstraints=False, matchTags=False, matchConstraints=False ) idx += 1 yield asn1Object def indefLenValueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if tagSet[0].tagFormat != tag.tagFormatConstructed: raise error.PyAsn1Error('Constructed tag format expected') if substrateFun is not None: if asn1Spec is not None: asn1Object = asn1Spec.clone() elif self.protoComponent is not None: asn1Object = self.protoComponent.clone(tagSet=tagSet) else: asn1Object = self.protoRecordComponent, self.protoSequenceComponent for chunk in substrateFun(asn1Object, substrate, length, options): yield chunk return if asn1Spec is None: for asn1Object in self._decodeComponentsSchemaless( substrate, tagSet=tagSet, decodeFun=decodeFun, length=length, **dict(options, allowEoo=True)): if isinstance(asn1Object, SubstrateUnderrunError): yield asn1Object yield asn1Object return asn1Object = asn1Spec.clone() asn1Object.clear() options = self._passAsn1Object(asn1Object, options) if asn1Spec.typeId in (univ.Sequence.typeId, univ.Set.typeId): namedTypes = asn1Object.componentType isSetType = asn1Object.typeId == univ.Set.typeId isDeterministic = not isSetType and not namedTypes.hasOptionalOrDefault if LOG: LOG('decoding %sdeterministic %s type %r chosen by type ID' % ( not isDeterministic and 'non-' or '', isSetType and 'SET' or '', asn1Spec)) seenIndices = set() idx = 0 while True: # loop over components if len(namedTypes) <= idx: asn1Spec = None elif isSetType: asn1Spec = namedTypes.tagMapUnique else: try: if isDeterministic: asn1Spec = namedTypes[idx].asn1Object elif namedTypes[idx].isOptional or namedTypes[idx].isDefaulted: asn1Spec = namedTypes.getTagMapNearPosition(idx) else: asn1Spec = namedTypes[idx].asn1Object except IndexError: raise error.PyAsn1Error( 'Excessive components decoded at %r' % (asn1Object,) ) for component in decodeFun(substrate, asn1Spec, allowEoo=True, **options): if isinstance(component, SubstrateUnderrunError): yield component if component is eoo.endOfOctets: break if component is eoo.endOfOctets: break if not isDeterministic and namedTypes: if isSetType: idx = namedTypes.getPositionByType(component.effectiveTagSet) elif namedTypes[idx].isOptional or namedTypes[idx].isDefaulted: idx = namedTypes.getPositionNearType(component.effectiveTagSet, idx) asn1Object.setComponentByPosition( idx, component, verifyConstraints=False, matchTags=False, matchConstraints=False ) seenIndices.add(idx) idx += 1 if LOG: LOG('seen component indices %s' % seenIndices) if namedTypes: if not namedTypes.requiredComponents.issubset(seenIndices): raise error.PyAsn1Error( 'ASN.1 object %s has uninitialized ' 'components' % asn1Object.__class__.__name__) if namedTypes.hasOpenTypes: openTypes = options.get('openTypes', {}) if LOG: LOG('user-specified open types map:') for k, v in openTypes.items(): LOG('%s -> %r' % (k, v)) if openTypes or options.get('decodeOpenTypes', False): for idx, namedType in enumerate(namedTypes.namedTypes): if not namedType.openType: continue if namedType.isOptional and not asn1Object.getComponentByPosition(idx).isValue: continue governingValue = asn1Object.getComponentByName( namedType.openType.name ) try: openType = openTypes[governingValue] except KeyError: if LOG: LOG('default open types map of component ' '"%s.%s" governed by component "%s.%s"' ':' % (asn1Object.__class__.__name__, namedType.name, asn1Object.__class__.__name__, namedType.openType.name)) for k, v in namedType.openType.items(): LOG('%s -> %r' % (k, v)) try: openType = namedType.openType[governingValue] except KeyError: if LOG: LOG('failed to resolve open type by governing ' 'value %r' % (governingValue,)) continue if LOG: LOG('resolved open type %r by governing ' 'value %r' % (openType, governingValue)) containerValue = asn1Object.getComponentByPosition(idx) if containerValue.typeId in ( univ.SetOf.typeId, univ.SequenceOf.typeId): for pos, containerElement in enumerate( containerValue): stream = asSeekableStream(containerValue[pos].asOctets()) for component in decodeFun(stream, asn1Spec=openType, **dict(options, allowEoo=True)): if isinstance(component, SubstrateUnderrunError): yield component if component is eoo.endOfOctets: break containerValue[pos] = component else: stream = asSeekableStream(asn1Object.getComponentByPosition(idx).asOctets()) for component in decodeFun(stream, asn1Spec=openType, **dict(options, allowEoo=True)): if isinstance(component, SubstrateUnderrunError): yield component if component is eoo.endOfOctets: break asn1Object.setComponentByPosition(idx, component) else: inconsistency = asn1Object.isInconsistent if inconsistency: raise error.PyAsn1Error( f"ASN.1 object {asn1Object.__class__.__name__} is inconsistent") else: componentType = asn1Spec.componentType if LOG: LOG('decoding type %r chosen by given `asn1Spec`' % componentType) idx = 0 while True: for component in decodeFun( substrate, componentType, allowEoo=True, **options): if isinstance(component, SubstrateUnderrunError): yield component if component is eoo.endOfOctets: break if component is eoo.endOfOctets: break asn1Object.setComponentByPosition( idx, component, verifyConstraints=False, matchTags=False, matchConstraints=False ) idx += 1 yield asn1Object class SequenceOrSequenceOfPayloadDecoder(ConstructedPayloadDecoderBase): protoRecordComponent = univ.Sequence() protoSequenceComponent = univ.SequenceOf() class SequencePayloadDecoder(SequenceOrSequenceOfPayloadDecoder): protoComponent = univ.Sequence() class SequenceOfPayloadDecoder(SequenceOrSequenceOfPayloadDecoder): protoComponent = univ.SequenceOf() class SetOrSetOfPayloadDecoder(ConstructedPayloadDecoderBase): protoRecordComponent = univ.Set() protoSequenceComponent = univ.SetOf() class SetPayloadDecoder(SetOrSetOfPayloadDecoder): protoComponent = univ.Set() class SetOfPayloadDecoder(SetOrSetOfPayloadDecoder): protoComponent = univ.SetOf() class ChoicePayloadDecoder(ConstructedPayloadDecoderBase): protoComponent = univ.Choice() def valueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if asn1Spec is None: asn1Object = self.protoComponent.clone(tagSet=tagSet) else: asn1Object = asn1Spec.clone() if substrateFun: for chunk in substrateFun(asn1Object, substrate, length, options): yield chunk return options = self._passAsn1Object(asn1Object, options) if asn1Object.tagSet == tagSet: if LOG: LOG('decoding %s as explicitly tagged CHOICE' % (tagSet,)) for component in decodeFun( substrate, asn1Object.componentTagMap, **options): if isinstance(component, SubstrateUnderrunError): yield component else: if LOG: LOG('decoding %s as untagged CHOICE' % (tagSet,)) for component in decodeFun( substrate, asn1Object.componentTagMap, tagSet, length, state, **options): if isinstance(component, SubstrateUnderrunError): yield component effectiveTagSet = component.effectiveTagSet if LOG: LOG('decoded component %s, effective tag set %s' % (component, effectiveTagSet)) asn1Object.setComponentByType( effectiveTagSet, component, verifyConstraints=False, matchTags=False, matchConstraints=False, innerFlag=False ) yield asn1Object def indefLenValueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if asn1Spec is None: asn1Object = self.protoComponent.clone(tagSet=tagSet) else: asn1Object = asn1Spec.clone() if substrateFun: for chunk in substrateFun(asn1Object, substrate, length, options): yield chunk return options = self._passAsn1Object(asn1Object, options) isTagged = asn1Object.tagSet == tagSet if LOG: LOG('decoding %s as %stagged CHOICE' % ( tagSet, isTagged and 'explicitly ' or 'un')) while True: if isTagged: iterator = decodeFun( substrate, asn1Object.componentType.tagMapUnique, **dict(options, allowEoo=True)) else: iterator = decodeFun( substrate, asn1Object.componentType.tagMapUnique, tagSet, length, state, **dict(options, allowEoo=True)) for component in iterator: if isinstance(component, SubstrateUnderrunError): yield component if component is eoo.endOfOctets: break effectiveTagSet = component.effectiveTagSet if LOG: LOG('decoded component %s, effective tag set ' '%s' % (component, effectiveTagSet)) asn1Object.setComponentByType( effectiveTagSet, component, verifyConstraints=False, matchTags=False, matchConstraints=False, innerFlag=False ) if not isTagged: break if not isTagged or component is eoo.endOfOctets: break yield asn1Object class AnyPayloadDecoder(AbstractSimplePayloadDecoder): protoComponent = univ.Any() def valueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if asn1Spec is None: isUntagged = True elif asn1Spec.__class__ is tagmap.TagMap: isUntagged = tagSet not in asn1Spec.tagMap else: isUntagged = tagSet != asn1Spec.tagSet if isUntagged: fullPosition = substrate.markedPosition currentPosition = substrate.tell() substrate.seek(fullPosition, os.SEEK_SET) length += currentPosition - fullPosition if LOG: for chunk in peekIntoStream(substrate, length): if isinstance(chunk, SubstrateUnderrunError): yield chunk LOG('decoding as untagged ANY, substrate ' '%s' % debug.hexdump(chunk)) if substrateFun: for chunk in substrateFun( self._createComponent(asn1Spec, tagSet, noValue, **options), substrate, length, options): yield chunk return for chunk in readFromStream(substrate, length, options): if isinstance(chunk, SubstrateUnderrunError): yield chunk yield self._createComponent(asn1Spec, tagSet, chunk, **options) def indefLenValueDecoder(self, substrate, asn1Spec, tagSet=None, length=None, state=None, decodeFun=None, substrateFun=None, **options): if asn1Spec is None: isTagged = False elif asn1Spec.__class__ is tagmap.TagMap: isTagged = tagSet in asn1Spec.tagMap else: isTagged = tagSet == asn1Spec.tagSet if isTagged: # tagged Any type -- consume header substrate chunk = b'' if LOG: LOG('decoding as tagged ANY') else: # TODO: Seems not to be tested fullPosition = substrate.markedPosition currentPosition = substrate.tell() substrate.seek(fullPosition, os.SEEK_SET) for chunk in readFromStream(substrate, currentPosition - fullPosition, options): if isinstance(chunk, SubstrateUnderrunError): yield chunk if LOG: LOG('decoding as untagged ANY, header substrate %s' % debug.hexdump(chunk)) # Any components do not inherit initial tag asn1Spec = self.protoComponent if substrateFun and substrateFun is not self.substrateCollector: asn1Object = self._createComponent( asn1Spec, tagSet, noValue, **options) for chunk in substrateFun( asn1Object, chunk + substrate, length + len(chunk), options): yield chunk return if LOG: LOG('assembling constructed serialization') # All inner fragments are of the same type, treat them as octet string substrateFun = self.substrateCollector while True: # loop over fragments for component in decodeFun( substrate, asn1Spec, substrateFun=substrateFun, allowEoo=True, **options): if isinstance(component, SubstrateUnderrunError): yield component if component is eoo.endOfOctets: break if component is eoo.endOfOctets: break chunk += component if substrateFun: yield chunk # TODO: Weird else: yield self._createComponent(asn1Spec, tagSet, chunk, **options) # character string types class UTF8StringPayloadDecoder(OctetStringPayloadDecoder): protoComponent = char.UTF8String() class NumericStringPayloadDecoder(OctetStringPayloadDecoder): protoComponent = char.NumericString() class PrintableStringPayloadDecoder(OctetStringPayloadDecoder): protoComponent = char.PrintableString() class TeletexStringPayloadDecoder(OctetStringPayloadDecoder): protoComponent = char.TeletexString() class VideotexStringPayloadDecoder(OctetStringPayloadDecoder): protoComponent = char.VideotexString() class IA5StringPayloadDecoder(OctetStringPayloadDecoder): protoComponent = char.IA5String() class GraphicStringPayloadDecoder(OctetStringPayloadDecoder): protoComponent = char.GraphicString() class VisibleStringPayloadDecoder(OctetStringPayloadDecoder): protoComponent = char.VisibleString() class GeneralStringPayloadDecoder(OctetStringPayloadDecoder): protoComponent = char.GeneralString() class UniversalStringPayloadDecoder(OctetStringPayloadDecoder): protoComponent = char.UniversalString() class BMPStringPayloadDecoder(OctetStringPayloadDecoder): protoComponent = char.BMPString() # "useful" types class ObjectDescriptorPayloadDecoder(OctetStringPayloadDecoder): protoComponent = useful.ObjectDescriptor() class GeneralizedTimePayloadDecoder(OctetStringPayloadDecoder): protoComponent = useful.GeneralizedTime() class UTCTimePayloadDecoder(OctetStringPayloadDecoder): protoComponent = useful.UTCTime() TAG_MAP = { univ.Integer.tagSet: IntegerPayloadDecoder(), univ.Boolean.tagSet: BooleanPayloadDecoder(), univ.BitString.tagSet: BitStringPayloadDecoder(), univ.OctetString.tagSet: OctetStringPayloadDecoder(), univ.Null.tagSet: NullPayloadDecoder(), univ.ObjectIdentifier.tagSet: ObjectIdentifierPayloadDecoder(), univ.RelativeOID.tagSet: RelativeOIDPayloadDecoder(), univ.Enumerated.tagSet: IntegerPayloadDecoder(), univ.Real.tagSet: RealPayloadDecoder(), univ.Sequence.tagSet: SequenceOrSequenceOfPayloadDecoder(), # conflicts with SequenceOf univ.Set.tagSet: SetOrSetOfPayloadDecoder(), # conflicts with SetOf univ.Choice.tagSet: ChoicePayloadDecoder(), # conflicts with Any # character string types char.UTF8String.tagSet: UTF8StringPayloadDecoder(), char.NumericString.tagSet: NumericStringPayloadDecoder(), char.PrintableString.tagSet: PrintableStringPayloadDecoder(), char.TeletexString.tagSet: TeletexStringPayloadDecoder(), char.VideotexString.tagSet: VideotexStringPayloadDecoder(), char.IA5String.tagSet: IA5StringPayloadDecoder(), char.GraphicString.tagSet: GraphicStringPayloadDecoder(), char.VisibleString.tagSet: VisibleStringPayloadDecoder(), char.GeneralString.tagSet: GeneralStringPayloadDecoder(), char.UniversalString.tagSet: UniversalStringPayloadDecoder(), char.BMPString.tagSet: BMPStringPayloadDecoder(), # useful types useful.ObjectDescriptor.tagSet: ObjectDescriptorPayloadDecoder(), useful.GeneralizedTime.tagSet: GeneralizedTimePayloadDecoder(), useful.UTCTime.tagSet: UTCTimePayloadDecoder() } # Type-to-codec map for ambiguous ASN.1 types TYPE_MAP = { univ.Set.typeId: SetPayloadDecoder(), univ.SetOf.typeId: SetOfPayloadDecoder(), univ.Sequence.typeId: SequencePayloadDecoder(), univ.SequenceOf.typeId: SequenceOfPayloadDecoder(), univ.Choice.typeId: ChoicePayloadDecoder(), univ.Any.typeId: AnyPayloadDecoder() } # Put in non-ambiguous types for faster codec lookup for typeDecoder in TAG_MAP.values(): if typeDecoder.protoComponent is not None: typeId = typeDecoder.protoComponent.__class__.typeId if typeId is not None and typeId not in TYPE_MAP: TYPE_MAP[typeId] = typeDecoder (stDecodeTag, stDecodeLength, stGetValueDecoder, stGetValueDecoderByAsn1Spec, stGetValueDecoderByTag, stTryAsExplicitTag, stDecodeValue, stDumpRawValue, stErrorCondition, stStop) = [x for x in range(10)] EOO_SENTINEL = bytes((0, 0)) class SingleItemDecoder(object): defaultErrorState = stErrorCondition #defaultErrorState = stDumpRawValue defaultRawDecoder = AnyPayloadDecoder() supportIndefLength = True TAG_MAP = TAG_MAP TYPE_MAP = TYPE_MAP def __init__(self, tagMap=_MISSING, typeMap=_MISSING, **ignored): self._tagMap = tagMap if tagMap is not _MISSING else self.TAG_MAP self._typeMap = typeMap if typeMap is not _MISSING else self.TYPE_MAP # Tag & TagSet objects caches self._tagCache = {} self._tagSetCache = {} def __call__(self, substrate, asn1Spec=None, tagSet=None, length=None, state=stDecodeTag, decodeFun=None, substrateFun=None, **options): allowEoo = options.pop('allowEoo', False) if LOG: LOG('decoder called at scope %s with state %d, working with up ' 'to %s octets of substrate: ' '%s' % (debug.scope, state, length, substrate)) # Look for end-of-octets sentinel if allowEoo and self.supportIndefLength: for eoo_candidate in readFromStream(substrate, 2, options): if isinstance(eoo_candidate, SubstrateUnderrunError): yield eoo_candidate if eoo_candidate == EOO_SENTINEL: if LOG: LOG('end-of-octets sentinel found') yield eoo.endOfOctets return else: substrate.seek(-2, os.SEEK_CUR) tagMap = self._tagMap typeMap = self._typeMap tagCache = self._tagCache tagSetCache = self._tagSetCache value = noValue substrate.markedPosition = substrate.tell() while state is not stStop: if state is stDecodeTag: # Decode tag isShortTag = True for firstByte in readFromStream(substrate, 1, options): if isinstance(firstByte, SubstrateUnderrunError): yield firstByte firstOctet = ord(firstByte) try: lastTag = tagCache[firstOctet] except KeyError: integerTag = firstOctet tagClass = integerTag & 0xC0 tagFormat = integerTag & 0x20 tagId = integerTag & 0x1F if tagId == 0x1F: isShortTag = False lengthOctetIdx = 0 tagId = 0 while True: for integerByte in readFromStream(substrate, 1, options): if isinstance(integerByte, SubstrateUnderrunError): yield integerByte if not integerByte: raise error.SubstrateUnderrunError( 'Short octet stream on long tag decoding' ) integerTag = ord(integerByte) lengthOctetIdx += 1 tagId <<= 7 tagId |= (integerTag & 0x7F) if not integerTag & 0x80: break lastTag = tag.Tag( tagClass=tagClass, tagFormat=tagFormat, tagId=tagId ) if isShortTag: # cache short tags tagCache[firstOctet] = lastTag if tagSet is None: if isShortTag: try: tagSet = tagSetCache[firstOctet] except KeyError: # base tag not recovered tagSet = tag.TagSet((), lastTag) tagSetCache[firstOctet] = tagSet else: tagSet = tag.TagSet((), lastTag) else: tagSet = lastTag + tagSet state = stDecodeLength if LOG: LOG('tag decoded into %s, decoding length' % tagSet) if state is stDecodeLength: # Decode length for firstOctet in readFromStream(substrate, 1, options): if isinstance(firstOctet, SubstrateUnderrunError): yield firstOctet firstOctet = ord(firstOctet) if firstOctet < 128: length = firstOctet elif firstOctet > 128: size = firstOctet & 0x7F # encoded in size bytes for encodedLength in readFromStream(substrate, size, options): if isinstance(encodedLength, SubstrateUnderrunError): yield encodedLength encodedLength = list(encodedLength) # missing check on maximum size, which shouldn't be a # problem, we can handle more than is possible if len(encodedLength) != size: raise error.SubstrateUnderrunError( '%s<%s at %s' % (size, len(encodedLength), tagSet) ) length = 0 for lengthOctet in encodedLength: length <<= 8 length |= lengthOctet size += 1 else: # 128 means indefinite length = -1 if length == -1 and not self.supportIndefLength: raise error.PyAsn1Error('Indefinite length encoding not supported by this codec') state = stGetValueDecoder if LOG: LOG('value length decoded into %d' % length) if state is stGetValueDecoder: if asn1Spec is None: state = stGetValueDecoderByTag else: state = stGetValueDecoderByAsn1Spec # # There're two ways of creating subtypes in ASN.1 what influences # decoder operation. These methods are: # 1) Either base types used in or no IMPLICIT tagging has been # applied on subtyping. # 2) Subtype syntax drops base type information (by means of # IMPLICIT tagging. # The first case allows for complete tag recovery from substrate # while the second one requires original ASN.1 type spec for # decoding. # # In either case a set of tags (tagSet) is coming from substrate # in an incremental, tag-by-tag fashion (this is the case of # EXPLICIT tag which is most basic). Outermost tag comes first # from the wire. # if state is stGetValueDecoderByTag: try: concreteDecoder = tagMap[tagSet] except KeyError: concreteDecoder = None if concreteDecoder: state = stDecodeValue else: try: concreteDecoder = tagMap[tagSet[:1]] except KeyError: concreteDecoder = None if concreteDecoder: state = stDecodeValue else: state = stTryAsExplicitTag if LOG: LOG('codec %s chosen by a built-in type, decoding %s' % (concreteDecoder and concreteDecoder.__class__.__name__ or "<none>", state is stDecodeValue and 'value' or 'as explicit tag')) debug.scope.push(concreteDecoder is None and '?' or concreteDecoder.protoComponent.__class__.__name__) if state is stGetValueDecoderByAsn1Spec: if asn1Spec.__class__ is tagmap.TagMap: try: chosenSpec = asn1Spec[tagSet] except KeyError: chosenSpec = None if LOG: LOG('candidate ASN.1 spec is a map of:') for firstOctet, v in asn1Spec.presentTypes.items(): LOG(' %s -> %s' % (firstOctet, v.__class__.__name__)) if asn1Spec.skipTypes: LOG('but neither of: ') for firstOctet, v in asn1Spec.skipTypes.items(): LOG(' %s -> %s' % (firstOctet, v.__class__.__name__)) LOG('new candidate ASN.1 spec is %s, chosen by %s' % (chosenSpec is None and '<none>' or chosenSpec.prettyPrintType(), tagSet)) elif tagSet == asn1Spec.tagSet or tagSet in asn1Spec.tagMap: chosenSpec = asn1Spec if LOG: LOG('candidate ASN.1 spec is %s' % asn1Spec.__class__.__name__) else: chosenSpec = None if chosenSpec is not None: try: # ambiguous type or just faster codec lookup concreteDecoder = typeMap[chosenSpec.typeId] if LOG: LOG('value decoder chosen for an ambiguous type by type ID %s' % (chosenSpec.typeId,)) except KeyError: # use base type for codec lookup to recover untagged types baseTagSet = tag.TagSet(chosenSpec.tagSet.baseTag, chosenSpec.tagSet.baseTag) try: # base type or tagged subtype concreteDecoder = tagMap[baseTagSet] if LOG: LOG('value decoder chosen by base %s' % (baseTagSet,)) except KeyError: concreteDecoder = None if concreteDecoder: asn1Spec = chosenSpec state = stDecodeValue else: state = stTryAsExplicitTag else: concreteDecoder = None state = stTryAsExplicitTag if LOG: LOG('codec %s chosen by ASN.1 spec, decoding %s' % (state is stDecodeValue and concreteDecoder.__class__.__name__ or "<none>", state is stDecodeValue and 'value' or 'as explicit tag')) debug.scope.push(chosenSpec is None and '?' or chosenSpec.__class__.__name__) if state is stDecodeValue: if not options.get('recursiveFlag', True) and not substrateFun: # deprecate this def substrateFun(asn1Object, _substrate, _length, _options): """Legacy hack to keep the recursiveFlag=False option supported. The decode(..., substrateFun=userCallback) option was introduced in 0.1.4 as a generalization of the old recursiveFlag=False option. Users should pass their callback instead of using recursiveFlag. """ yield asn1Object original_position = substrate.tell() if length == -1: # indef length for value in concreteDecoder.indefLenValueDecoder( substrate, asn1Spec, tagSet, length, stGetValueDecoder, self, substrateFun, **options): if isinstance(value, SubstrateUnderrunError): yield value else: for value in concreteDecoder.valueDecoder( substrate, asn1Spec, tagSet, length, stGetValueDecoder, self, substrateFun, **options): if isinstance(value, SubstrateUnderrunError): yield value bytesRead = substrate.tell() - original_position if not substrateFun and bytesRead != length: raise PyAsn1Error( "Read %s bytes instead of expected %s." % (bytesRead, length)) elif substrateFun and bytesRead > length: # custom substrateFun may be used for partial decoding, reading less is expected there raise PyAsn1Error( "Read %s bytes are more than expected %s." % (bytesRead, length)) if LOG: LOG('codec %s yields type %s, value:\n%s\n...' % ( concreteDecoder.__class__.__name__, value.__class__.__name__, isinstance(value, base.Asn1Item) and value.prettyPrint() or value)) state = stStop break if state is stTryAsExplicitTag: if (tagSet and tagSet[0].tagFormat == tag.tagFormatConstructed and tagSet[0].tagClass != tag.tagClassUniversal): # Assume explicit tagging concreteDecoder = rawPayloadDecoder state = stDecodeValue else: concreteDecoder = None state = self.defaultErrorState if LOG: LOG('codec %s chosen, decoding %s' % (concreteDecoder and concreteDecoder.__class__.__name__ or "<none>", state is stDecodeValue and 'value' or 'as failure')) if state is stDumpRawValue: concreteDecoder = self.defaultRawDecoder if LOG: LOG('codec %s chosen, decoding value' % concreteDecoder.__class__.__name__) state = stDecodeValue if state is stErrorCondition: raise error.PyAsn1Error( '%s not in asn1Spec: %r' % (tagSet, asn1Spec) ) if LOG: debug.scope.pop() LOG('decoder left scope %s, call completed' % debug.scope) yield value class StreamingDecoder(object): """Create an iterator that turns BER/CER/DER byte stream into ASN.1 objects. On each iteration, consume whatever BER/CER/DER serialization is available in the `substrate` stream-like object and turns it into one or more, possibly nested, ASN.1 objects. Parameters ---------- substrate: :py:class:`file`, :py:class:`io.BytesIO` BER/CER/DER serialization in form of a byte stream Keyword Args ------------ asn1Spec: :py:class:`~pyasn1.type.base.PyAsn1Item` A pyasn1 type object to act as a template guiding the decoder. Depending on the ASN.1 structure being decoded, `asn1Spec` may or may not be required. One of the reasons why `asn1Spec` may me required is that ASN.1 structure is encoded in the *IMPLICIT* tagging mode. Yields ------ : :py:class:`~pyasn1.type.base.PyAsn1Item`, :py:class:`~pyasn1.error.SubstrateUnderrunError` Decoded ASN.1 object (possibly, nested) or :py:class:`~pyasn1.error.SubstrateUnderrunError` object indicating insufficient BER/CER/DER serialization on input to fully recover ASN.1 objects from it. In the latter case the caller is advised to ensure some more data in the input stream, then call the iterator again. The decoder will resume the decoding process using the newly arrived data. The `context` property of :py:class:`~pyasn1.error.SubstrateUnderrunError` object might hold a reference to the partially populated ASN.1 object being reconstructed. Raises ------ ~pyasn1.error.PyAsn1Error, ~pyasn1.error.EndOfStreamError `PyAsn1Error` on deserialization error, `EndOfStreamError` on premature stream closure. Examples -------- Decode BER serialisation without ASN.1 schema .. code-block:: pycon >>> stream = io.BytesIO( ... b'0\t\x02\x01\x01\x02\x01\x02\x02\x01\x03') >>> >>> for asn1Object in StreamingDecoder(stream): ... print(asn1Object) >>> SequenceOf: 1 2 3 Decode BER serialisation with ASN.1 schema .. code-block:: pycon >>> stream = io.BytesIO( ... b'0\t\x02\x01\x01\x02\x01\x02\x02\x01\x03') >>> >>> schema = SequenceOf(componentType=Integer()) >>> >>> decoder = StreamingDecoder(stream, asn1Spec=schema) >>> for asn1Object in decoder: ... print(asn1Object) >>> SequenceOf: 1 2 3 """ SINGLE_ITEM_DECODER = SingleItemDecoder def __init__(self, substrate, asn1Spec=None, **options): self._singleItemDecoder = self.SINGLE_ITEM_DECODER(**options) self._substrate = asSeekableStream(substrate) self._asn1Spec = asn1Spec self._options = options def __iter__(self): while True: for asn1Object in self._singleItemDecoder( self._substrate, self._asn1Spec, **self._options): yield asn1Object for chunk in isEndOfStream(self._substrate): if isinstance(chunk, SubstrateUnderrunError): yield break if chunk: break class Decoder(object): """Create a BER decoder object. Parse BER/CER/DER octet-stream into one, possibly nested, ASN.1 object. """ STREAMING_DECODER = StreamingDecoder @classmethod def __call__(cls, substrate, asn1Spec=None, **options): """Turns BER/CER/DER octet stream into an ASN.1 object. Takes BER/CER/DER octet-stream in form of :py:class:`bytes` and decode it into an ASN.1 object (e.g. :py:class:`~pyasn1.type.base.PyAsn1Item` derivative) which may be a scalar or an arbitrary nested structure. Parameters ---------- substrate: :py:class:`bytes` BER/CER/DER octet-stream to parse Keyword Args ------------ asn1Spec: :py:class:`~pyasn1.type.base.PyAsn1Item` A pyasn1 type object (:py:class:`~pyasn1.type.base.PyAsn1Item` derivative) to act as a template guiding the decoder. Depending on the ASN.1 structure being decoded, `asn1Spec` may or may not be required. Most common reason for it to require is that ASN.1 structure is encoded in *IMPLICIT* tagging mode. substrateFun: :py:class:`Union[ Callable[[pyasn1.type.base.PyAsn1Item, bytes, int], Tuple[pyasn1.type.base.PyAsn1Item, bytes]], Callable[[pyasn1.type.base.PyAsn1Item, io.BytesIO, int, dict], Generator[Union[pyasn1.type.base.PyAsn1Item, pyasn1.error.SubstrateUnderrunError], None, None]] ]` User callback meant to generalize special use cases like non-recursive or partial decoding. A 3-arg non-streaming variant is supported for backwards compatiblilty in addition to the newer 4-arg streaming variant. The callback will receive the uninitialized object recovered from substrate as 1st argument, the uninterpreted payload as 2nd argument, and the length of the uninterpreted payload as 3rd argument. The streaming variant will additionally receive the decode(..., **options) kwargs as 4th argument. The non-streaming variant shall return an object that will be propagated as decode() return value as 1st item, and the remainig payload for further decode passes as 2nd item. The streaming variant shall yield an object that will be propagated as decode() return value, and leave the remaining payload in the stream. Returns ------- : :py:class:`tuple` A tuple of :py:class:`~pyasn1.type.base.PyAsn1Item` object recovered from BER/CER/DER substrate and the unprocessed trailing portion of the `substrate` (may be empty) Raises ------ : :py:class:`~pyasn1.error.PyAsn1Error` :py:class:`~pyasn1.error.SubstrateUnderrunError` on insufficient input or :py:class:`~pyasn1.error.PyAsn1Error` on decoding error. Examples -------- Decode BER/CER/DER serialisation without ASN.1 schema .. code-block:: pycon >>> s, unprocessed = decode(b'0\t\x02\x01\x01\x02\x01\x02\x02\x01\x03') >>> str(s) SequenceOf: 1 2 3 Decode BER/CER/DER serialisation with ASN.1 schema .. code-block:: pycon >>> seq = SequenceOf(componentType=Integer()) >>> s, unprocessed = decode( b'0\t\x02\x01\x01\x02\x01\x02\x02\x01\x03', asn1Spec=seq) >>> str(s) SequenceOf: 1 2 3 """ substrate = asSeekableStream(substrate) if "substrateFun" in options: origSubstrateFun = options["substrateFun"] def substrateFunWrapper(asn1Object, substrate, length, options=None): """Support both 0.4 and 0.5 style APIs. substrateFun API has changed in 0.5 for use with streaming decoders. To stay backwards compatible, we first try if we received a streaming user callback. If that fails,we assume we've received a non-streaming v0.4 user callback and convert it for streaming on the fly """ try: substrate_gen = origSubstrateFun(asn1Object, substrate, length, options) except TypeError as _value: if _value.__traceback__.tb_next: # Traceback depth > 1 means TypeError from inside user provided function raise # invariant maintained at Decoder.__call__ entry assert isinstance(substrate, io.BytesIO) # nosec assert_used substrate_gen = Decoder._callSubstrateFunV4asV5(origSubstrateFun, asn1Object, substrate, length) for value in substrate_gen: yield value options["substrateFun"] = substrateFunWrapper streamingDecoder = cls.STREAMING_DECODER( substrate, asn1Spec, **options) for asn1Object in streamingDecoder: if isinstance(asn1Object, SubstrateUnderrunError): raise error.SubstrateUnderrunError('Short substrate on input') try: tail = next(readFromStream(substrate)) except error.EndOfStreamError: tail = b'' return asn1Object, tail @staticmethod def _callSubstrateFunV4asV5(substrateFunV4, asn1Object, substrate, length): substrate_bytes = substrate.read() if length == -1: length = len(substrate_bytes) value, nextSubstrate = substrateFunV4(asn1Object, substrate_bytes, length) nbytes = substrate.write(nextSubstrate) substrate.truncate() substrate.seek(-nbytes, os.SEEK_CUR) yield value #: Turns BER octet stream into an ASN.1 object. #: #: Takes BER octet-stream and decode it into an ASN.1 object #: (e.g. :py:class:`~pyasn1.type.base.PyAsn1Item` derivative) which #: may be a scalar or an arbitrary nested structure. #: #: Parameters #: ---------- #: substrate: :py:class:`bytes` #: BER octet-stream #: #: Keyword Args #: ------------ #: asn1Spec: any pyasn1 type object e.g. :py:class:`~pyasn1.type.base.PyAsn1Item` derivative #: A pyasn1 type object to act as a template guiding the decoder. Depending on the ASN.1 structure #: being decoded, *asn1Spec* may or may not be required. Most common reason for #: it to require is that ASN.1 structure is encoded in *IMPLICIT* tagging mode. #: #: Returns #: ------- #: : :py:class:`tuple` #: A tuple of pyasn1 object recovered from BER substrate (:py:class:`~pyasn1.type.base.PyAsn1Item` derivative) #: and the unprocessed trailing portion of the *substrate* (may be empty) #: #: Raises #: ------ #: ~pyasn1.error.PyAsn1Error, ~pyasn1.error.SubstrateUnderrunError #: On decoding errors #: #: Notes #: ----- #: This function is deprecated. Please use :py:class:`Decoder` or #: :py:class:`StreamingDecoder` class instance. #: #: Examples #: -------- #: Decode BER serialisation without ASN.1 schema #: #: .. code-block:: pycon #: #: >>> s, _ = decode(b'0\t\x02\x01\x01\x02\x01\x02\x02\x01\x03') #: >>> str(s) #: SequenceOf: #: 1 2 3 #: #: Decode BER serialisation with ASN.1 schema #: #: .. code-block:: pycon #: #: >>> seq = SequenceOf(componentType=Integer()) #: >>> s, _ = decode(b'0\t\x02\x01\x01\x02\x01\x02\x02\x01\x03', asn1Spec=seq) #: >>> str(s) #: SequenceOf: #: 1 2 3 #: decode = Decoder() def __getattr__(attr: str): if newAttr := {"tagMap": "TAG_MAP", "typeMap": "TYPE_MAP"}.get(attr): warnings.warn(f"{attr} is deprecated. Please use {newAttr} instead.", DeprecationWarning) return globals()[newAttr] raise AttributeError(attr)